The present invention is directed toward an anti-flameout safety system for a gas turbine engine, particularly such a safety system which prevents engine flameout in the event of entry of hail or water through the engine intake.
Typical gas turbine engines comprise at least one upstream axial compressor which compresses the air taken in through the engine intake and supplies the compressed air to a combustion chamber to be mixed with suitable fuel and burned. Such axial compressors typically have front air intakes for the air flow required for good gas turbine engine operation. However, when operated in adverse atmospheric conditions, the gas turbine engines also may take in significant quantities of hail and/or water such as, for instance, when the aircraft on which the engine is mounted passes through storms or clouds. The hail and/or water taken into the gas turbine engine may cause malfunctioning of the engine.
If the gas turbine engine is operating at full power, the compressor raises the temperature of the air passing through it so that any water contained in the air is vaporized. Thus, under these operating conditions, the hail and/or water does not cause extinction of the flame in the combustion chamber, known as flameout.
When the aircraft is operating under low engine power conditions, such as, for instance, during a landing approach, the compression ratio of the compressor is small. In this instance, the increase in temperature of the compressed air as it passes through the compressor may be insufficient to vaporize water present in the air so that water may arrive, either in a liquid state or in the form of ice particles, at the combustion chamber and cause flameout of one or more burners, and possibly even of the entire combustion chamber, thereby causing engine flameout. Quite obviously, engine flameout has serious consequences during all aircraft operating conditions, especially during a landing approach.
The prior art has attempted to solve the problem of hail or water in the intake gases by placing mechanical obstacles in the path of the air. These devices have included centrifugal separators, scoops, or nose cowls which force the hail or water particles to undergo deflection such that they may be removed from the intake air. However, such devices have proven to be unduly complex and have fallen short of achieving their objectives.
Another solution has been to have the aircraft pilot manually operate the throttles to increase engine power when the aircraft passes through heavy rains or storms which may cause engine malfunction due to the high concentrations of water in the intake air. Such a solution has not proven to be effective, since it requires the manual intervention of the aircraft pilot.